Stress distributions of steady and unsteady state hopper flows

Numerical study of the granular flow in a hopper is of great importance and has been a research focus worldwide for years (Langston et al. 1995; Seville et al. 1997; Cleary & Sawley 2002; Zhu &Yu 2004a). It provides a class of benchmark boundary-value problems for analyzing and predicting the behavior of granular materials under external mechanical excitations.